MEM devices have many applications for forming any variety of microsensors, microactuators, and other microcomponents. The term “microcomponent” is used herein generically to encompass sub-millimeter electronic/mechanical components, as well as MEM devices, MEM Systems (MEMS) components, and nanoelectromechanical (NEM) devices and systems (NEMS). Microcomponents include such devices as grippers, connectors, relays, and the like. Because of the size of the components and the relative size of the elements that make up these components, it is generally important to have precise positioning, especially in fastening applications. Unless the two devices to be connected or fastened are positioned correctly, the resulting joint may not be properly fit.
Furthermore, in some applications, grippers, connectors, receptacles, and the like, typically consume considerable energy to be “held” in an open and/or closed position. Therefore, in the application of a gripper, for example, electricity may be applied to hold the gripper either open or closed, depending on the design of the gripper. Thus, if the gripper must hold an item for an extended period of time, the electricity must be applied continuously. If, during the holding period, the electricity cannot be maintained, the gripper may let go of the item resulting in possible loss or damage.
It is advantageous to have a microcomponent capable of storing potential energy that can then be used to drive another action of the microcomponent. One current system that stores potential energy in connecting and fastening devices is described in U.S. Pat. No. 5,806,152 issued to Saitou et al., (Saitou). FIG. 1 is a schematic top view of a connecting device configured with a latching mechanism to hold the device in an open position, as described in Saitou. Fastener 10 includes outer latch 101 and inner latch mechanism 102. To facilitate proper operation of fastener 10, outer latch 101 is anchored to the substrate at 104, and inner latch 102 is anchored to the substrate at 105.
In operation, fastener 10 is cocked by depressing fastener 10 at 108. As 108 moves toward the foot of the device, latches 107 will be inserted into holders 106 forming a latched, friction fit. The latching action, thus, stores the potential energy applied in depressing fastener 10 at 108. Fastener 10 is then held in an open position without applied electricity or other continuous energy. As cocked fastener 10 is used to pick up object 103, the top of object 103 engages inner latch 102 which would then cause latches 107 to be removed from holder 106. Fastener 10 would then snap into a locked position with latches 109 clamping into holders 110 to hold object 103 in place. The potential energy stored in the latching process increases the clamping force which has the effect of self-positioning object 103.
The problem with the Saitou device is that it is anchored to the substrate, and thus, not very mobile. Furthermore, the holding mechanism relies on the strength and formation of the latches and latch-holders and the frictional forces between the latches and the latch-holder. Therefore, if a latch is misformed during manufacture or is deformed through an external force, the latch would not typically hold securely and could not store the potential energy in the device. Additionally, the latch portion may also shear off if an excessive amount of stressed is placed on the device.